Such an element is known from DE 199 62 177 A1, in which the travel-transmitting element has a pressure-loaded storage chamber area, the boundaries of which are elastically formed. Despite the different coefficients of thermal expansion that exist among the individual components within injection valves (e.g., ceramic, steel and hydraulic fluid), this thermal compensating element can make a positive tie between the individual components of an injection valve in the overall operating range; it is important to take into account among other things the steadiness of the rotational speed in respect of the travel-transmitting element. According to DE 199 62 177 A1 the storage chamber area is bounded by a sprung bellows arrangement made of metal. The first disadvantage of this is that metal bellows arrangements are costly to manufacture and therefore, relatively expensive. Since metal bellows are very stiff in the radial direction, volume compensation takes place in the axial direction. Metal bellows exhibit a linear spring characteristic during small displacements only. During larger displacements, such as can occur, for example, during an operating temperature variation, the bellows show marked hysteresis effects. Due to the settlement and hysteresis properties of the individual bellows, an additional spring element is necessary in order to ensure perpetuation of the storage chamber pressure and thereby, the ability to operate even at high engine speeds. Another disadvantage in the case of this metal bellows arrangement is that the dynamic characteristics can change during operation.
Alternatively, according to DE 199 62 177 A1 the storage chamber area with the elastically formed boundaries can also be made from elastomeric material. Volume compensation can then be achieved by radial movement of the bellows. In the axial direction, these elements are relatively soft, which is necessary in order for the actuator to generate sufficient travel. However, known elastomeric materials exhibit creep properties, and in the course of inevitable ageing, this leads to a loss of radial stiffness and in turn to an unwelcome loss of pressure in the storage chamber. Therefore, steadiness of the rotational speed would not be provided even in the case of an elastomeric bellows-type member.